Drying equipment



3957 K. H. NO'RLYNG 3,

DRYING EQUIPMENT Filed Sept. 21, 1965 2 Sheets-$heet 1 INVEN TOR. Kmsiian Hl'mme/s-L wqp Nor/ 07 Gilt 1957 K. H. NORLYNG DRYING EQUIPMENT 2Sheets-Sheet 2 Filed Sept. 21, 1965:

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United States Patent 3,348,318 DRYING EQUIPMENT Kristian HimmelstrupNorlyng, Copenhagen, Denmark,

assignor to Aktieselskahet Bing & Grondahls Porcellaenslabrik(Porcelainfabrikerne Bing & Grondahl 0g Nor-den A/S), Copenhagen,Denmark Filed Sept. 21, 1965, Ser. No. 488,898 Claims priority,application Denmark, Sept. 23, 1964, 4,671/64 3 Claims. (Cl. 34105) Thisinvention is concerned with a method and an equipment for the predryingof ceramic bodies by means of hot air, preferably moderately heated air,and has for its object to describe a method and an equipment by which itis possible to obtain a rapid and effective predrying without the riskthat such rapid drying should cause disadvantages, such as deformationor cracking of the ceramic bodies.

Drying equipments of this kind are used for instance in the porcelainindustry where pre-shaped soft plastic bodies have to be pre-dried andwhere a rapid pre-drying is of the greatest importance due to the factthat thereby it is possible to obtain that the normally used plastermoulds will be ready for re-use relatively quickly. It has to bementioned that the predrying necessarily must take place while thebodies are supported on these moulds.

After the termination of the predrying the pre-dried bodies may beremoved from the plaster mould and the drying process may be continuedin any convenient manner.

By the previously known drying equipments it has not been possible toaccelerate the pre-drying without the risk of a considerable cracking ofthe ceramic bodies. It has now been proved that these disadvantagesmight be avoided by a drying equipment which for each object to be driedhas a nozzle aggregate with a number of elongated tube-shaped nozzlesextending from the bottom of an air pressured chamber, the nozzles beingpositioned substantially mutually parallel and in such a manner that thestream of air formed by all the nozzles together will have a sectionalshape which is substantially the same as a plane vertical projection ofthe body and coinciding therewith. It has further been proved that themost favor able drying conditions are obtained when the openings of thenozzles and the air pressure are adapted in such a manner that thedrying air is leaving the nozzles with a velocity of at least 10,preferably 15-20 meter per second, or even more.

The invention shall further be explained in connection with the drawingshowing in FIGURE 1 a side view of a drying equipment in accordance withthe invention, the casing being partly cut away in order to show theinterior arrangements and FIGURE 2 showing a side view and partialvertical cross-section of a nozzle aggregate from such equipment.

In FIG. 1 is shown a drying equipment consisting of a casing 1surrounding a transportating system by which a chain 2 running overwheels 3 is carrying a number of swing carriers 4 each carrying aplaster mould 5. It will be observed that on each of the plaster mouldscarried by the swing carrier on the left hand and the upper part of thechain a plate or saucer 6 is placed. The casing is provided with anopening 7 through which the saucers might be romevd from the mould andconsequently the swing carriers on the right hand part of the chain hasno saucers placed thereon. The removing of the saucers and thereplacement of the moulds with other moulds on which plates or saucersare placed, do not belong to the invention and is therefore not furtherdescribed.

At the horizontal parts of the chains there are in the casing provided anumber of nozzle aggregate 8 and such a nozzle aggregate is shown inFIG. 2 in a larger scale and shall be further explained below.

In FIG. 2 is shown a part of a supporting plate 9, of a swing carrierand on this supporting plate is shown a plaster mould 5 on which again asaucer 6 is placed. Above this saucer the nozzle aggregate 8 ispositioned and it consists of a flat air chamber 10 having an air supplytube 11 for moderately preheated drying air under a certain pressure. Anumber of elongated tube-shaped air nozzles 12 are attached to thebottom of said chamber so that the dlying air might be let through thesenozzles against the plate 6 and thereby cause an accelerated predrying.The elongated nozzles 6 are intended for imposing to the air aconsiderable velocity and simultaneously allow the drying air which hasalready contacted the upward surface of the plate 6 to escape upwardlybetween the nozzles 12. The number of nozzles, the distribution thereof,the distance between adjacent nozzles, the diameter of each nozzle aswell as the velocity of the air, may be varied in regard to the size andshape of the object to be dried. The nozzle aggregate may also be usedin different manners. It is, for instance, possible to move the objectto be dried stepwise so that in a certain period it is standingcoaxially with one aggregate and during the next step it will standbelow another aggregate. It is also possible to let the moulds with theobjects move continuously when simultaneously the nozzle aggregate isadapted to follow the moulds along a considerable distance of themovement of the moulds. Further, the mould as well as the nozzleaggregate could be stationary during the whole predrying period thusremaining in their mutual coaxial position.

By the use of such an equipment the total air stream is concentratedagainst the object and the air reflected from the object will not-as itis usual with the previously known equipments-in any respect distort thestreams of air directed against the objects as the air can pass upward-sbetween the tube-shaped nozzles and therefrom escape in the space aroundthe nozzle aggregates where there is no real beam of air and where theair consequently in a relatively big space may pass to a sucking placevery smoothly and without influence of any kind of the concentrated airbeams coming from each of the nozzle aggregates.

In this connection it should be mentioned that the rapid drying is onlyobtainable by means of a stream of air with a considerable velocity dueto the fact that during this first phase of the drying process it is notpossible to use a drying air with a very high temperature. Consequentlya rather big amount of air with a moderate heating has to be used.

The big number of nozzles will of course cause a drying in spots but thespots will be placed so close to one another that they are mergingduring the continuation of the drying process so that for instance asaucer or a plate will obtain very uniform drying conditions. Thetensions which are caused during the drying process due to the shrinkageof the object will be distributed with very small tension gradientsnotwithstanding the rather rapid drying. As soon as the drying air hasreleased its contents of heat and has absorbed an amount of moisture itmay easily escape upwardly between the elongated nozzle tubes withouteffecting in any undesired manner the drying air which is blowndownwards from the nozzles.

The cross-section of the aggregate should approximately be of the samesize as the body to be dried and this body should also be positionedcoaxially with the aggregate in order to avoid any loss of energy todrying air which is not utilized. Simultaneously the air will then havethe best possibilities for getting away without doing any harm.

What is claimed is:

1. An apparatus for drying ceramic bodies as they are transported alonga horizontal path, said apparatus comprising a casing extending abovesaid path and containing at least one air pressure chamber and airoutlet means; a nozzle aggregate for each ceramic body to be dried, eachaggregate comprising a plurality of elongated parallel noules extendingdownwardly from said chamber to the vicinity of said path, and means tosupply air to said chamber at a predetermined pressure so that it passesthrough said nozzles, contacts the surfaces of said bodies, and is thenreflected upwardly therefrom, said nozzles being spaced apartsufficiently to allow the reflected gases to flow therethrough towardssaid air outlet means, the spacing between the discharge end of saidnozzles and said ceramic body being such that the refiected gas will notimpinge on the discharge from the nozzles.

2. An apparatus as claimed in claim 1, further comprising a conveyor onwhich said bodies are supported, said conveyor being adapted forstepwise conveyance of the bodies, each step corresponding to thedistance between adjacent nozzle aggregates.

3. An apparatus as claimed in claim 1, wherein said air outlet means areformed in the spaces between said nozzle aggregates.

References Cited Duff et a1. 34-105 KENNETH W. SPRAGUE, PrimaryExaminer.

1. AN APPARATUS FOR DRYING CERAMIC BODIES AS THEY ARE TRANSPORTED ALONGA HORIZONTAL PATH, SAID APPARATUS COMPRISING A CASING EXTENDING ABOVESAID PATH AND CONTAINING AT LEAST ONE AIR PRESSURE CHAMBER AND AIROUTLET MEANS; A NOZZLE AGGREGATE FOR EACH CERAMIC BODY TO BE DRIED; EACHAGGREGATE COMPRISING A PLURALITY OF ELONGATED PARALLEL NOZZLES EXTENDINGDOWNWARDLY FROM SAID CHAMBER TO THE VICINITY OF SAID PATH, AND MEANS TOSUPPLY AIR TO SAID CHAMBER AT A PREDETERMINED PRESSURE SO THAT IT PASSESTHROUGH SAID NOZZLES, CONTACT THE SURFACES OF SAID BODIES, AND IS THENREFLECTED UPWARDLY THEREFROM, SAID NOZZLES BEING SPACED APARTSUFFICIENTLY TO ALLOW THE REFLECTED GASES TO FLOW THERETHROUGH TOWARDSSAID AIR OUTLET MEANS, THE SPACING BETWEEN THE DISCHARGE END OF SAIDNOZZLES AND SAID CERAMIC BODY BEING SUCH THAT THE REFLECTED GAS WILL NOTIMPRINGE ON THE DISHCHARGE FROM THE NOZZLES.